// FEATURE: private void subset() { }
// FEATURE: grow if we run out of slots
+// FEATURE: Add the cached_index stuff back in
+
/** a weight-balanced tree with fake leaves */
public class BalancedTree {
-
+ private static final boolean DEBUG = true;
// Instance Variables ///////////////////////////////////////////////////////////////////
private int cached_index = -1;
private int cached_slot = -1;
-
+
// Public API //////////////////////////////////////////////////////////////////////////
/** the number of elements in the tree */
- public final int treeSize() { return root == 0 ? 0 : size[root]; }
+ public final int treeSize() {
+ synchronized(BalancedTree.class) {
+ return root == 0 ? 0 : size[root];
+ }
+ }
/** clamps index to [0..treeSize()] and inserts object o *before* the specified index */
- public final synchronized void insertNode(int index, Object o) {
+ public final void insertNode(int index, Object o) {
+ synchronized(BalancedTree.class) {
if(o == null) throw new Error("can't insert nulls in the balanced tree");
cached_slot = cached_index = -1;
if (index < 0) index = 0;
left[arg] = right[arg] = parent[arg] = 0;
size[arg] = 1;
}
+ if(DEBUG) check();
+ }
}
/** clamps index to [0..treeSize()-1] and replaces the object at that index with object o */
- public final synchronized void replaceNode(int index, Object o) {
+ public final void replaceNode(int index, Object o) {
+ synchronized(BalancedTree.class) {
if(o == null) throw new Error("can't insert nulls in the balanced tree");
cached_slot = cached_index = -1;
if(root == 0) throw new Error("called replaceNode() on an empty tree");
if (index >= treeSize()) index = treeSize() - 1;
int arg = allocateSlot(o);
insert(index, arg, root, 0, true, false);
+ if(DEBUG) check();
+ }
}
/** returns the index of o; runs in O((log n)^2) time unless cache hit */
- public final synchronized int indexNode(Object o) {
+ public final int indexNode(Object o) {
+ synchronized(BalancedTree.class) {
if(o == null) return -1;
if (cached_slot != -1 && objects[cached_slot] == o) return cached_index;
index++;
}
return index;
+ }
}
/** returns the object at index; runs in O(log n) time unless cache hit */
- public final synchronized Object getNode(int index) {
+ public final Object getNode(int index) {
+ synchronized(BalancedTree.class) {
if (index == cached_index) return objects[cached_slot];
if (cached_index != -1) {
return objects[cached_slot];
*/
return objects[get(index, root)];
+ }
}
/** deletes the object at index, returning the deleted object */
- public final synchronized Object deleteNode(int index) {
+ public final Object deleteNode(int index) {
+ synchronized(BalancedTree.class) {
cached_slot = cached_index = -1;
// FIXME: left[], right[], size[], and parent[] aren't getting cleared properly somewhere in here where a node had two children
int del = delete(index, root, 0);
left[del] = right[del] = size[del] = parent[del] = 0;
Object ret = objects[del];
objects[del] = null;
+ if(DEBUG) check();
return ret;
+ }
}
- public final synchronized void clear() {
+ public final void clear() {
+ synchronized(BalancedTree.class) {
if(root == 0) return;
int i = leftmost(root);
do {
i = next;
} while(i != 0);
root = 0;
+ }
+ if(DEBUG) check();
}
-
- protected void finalize() { clear(); }
-
// Node Data /////////////////////////////////////////////////////////////////////////
int odest = dest;
boolean plus = true;
int tries = 1;
+ if(dest == 0) dest=1;
while (objects[dest] != search || !(alloc || root(dest) == root)) {
- if (dest == 0) dest++;
dest = Math.abs((odest + (plus ? 1 : -1) * tries * tries) % objects.length);
+ if (dest == 0) dest=1;
if (plus) tries++;
plus = !plus;
// FEATURE: GROW - if(tries > MAX_SLOT_DISTANCE) return -1;
// Helpers /////////////////////////////////////////////////////////////////////////
+ // FEATURE: These might be faster if they aren't recursive
private final int leftmost(int slot) { return left[slot] <= 0 ? slot : leftmost(left[slot]); }
private final int rightmost(int slot) { return right[slot] <= 0 ? slot : rightmost(right[slot]); }
- private final int next(int slot) { return right[slot] <= 0 ? -1 * right[slot] : leftmost(right[slot]); }
- private final int prev(int slot) { return left[slot] <= 0 ? -1 * left[slot] : rightmost(left[slot]); }
private final int sizeof(int slot) { return slot <= 0 ? 0 : size[slot]; }
private final int root(int slot) { return parent[slot] == 0 ? slot : root(parent[slot]); }
+ private int next(int node) {
+ if(right[node] > 0) {
+ node = right[node];
+ while(left[node] > 0) node = left[node];
+ return node;
+ } else {
+ int p = parent[node];
+ while(right[p] == node) { node = p; p = parent[node]; };
+ return p;
+ }
+ }
+
+ private int prev(int node) {
+ if(left[node] > 0) {
+ node = left[node];
+ while(right[node] > 0) node = right[node];
+ return node;
+ } else {
+ int p = parent[node];
+ while(left[p] == node) { node = p; p = parent[node]; }
+ return p;
+ }
+ }
// Rotation and Balancing /////////////////////////////////////////////////////////////
int[] right = toTheLeft ? BalancedTree.right : BalancedTree.left;
int d = right[b];
int c = left[d];
- if (d <= 0) throw new Error("rotation error");
+ if (d == 0) throw new Error("rotation error");
left[d] = b;
- right[b] = c <= 0 ? -d : c;
+ right[b] = c;
parent[b] = d;
parent[d] = p;
- if(c > 0) parent[c] = b;
+ if(c != 0) parent[c] = b;
+
if (p == 0) root = d;
else if (left[p] == b) left[p] = d;
else if (right[p] == b) right[p] = d;
else throw new Error("rotate called with invalid parent");
size[b] = 1 + sizeof(left[b]) + sizeof(right[b]);
- size[d] = 1 + sizeof(left[d]) + sizeof(right[d]);
+ size[d] = 1 + sizeof(left[d]) + sizeof(right[d]);
}
private void balance(int slot, int p) {
// Insert /////////////////////////////////////////////////////////////////////////
private void insert(int index, int arg, int slot, int p, boolean replace, boolean wentLeft) {
- int diff = slot <= 0 ? 0 : index - sizeof(left[slot]);
- if (slot > 0 && diff != 0) {
+ int diff = slot == 0 ? 0 : index - sizeof(left[slot]);
+ if (slot != 0 && diff != 0) {
if (diff < 0) insert(index, arg, left[slot], slot, replace, true);
else insert(index - sizeof(left[slot]) - 1, arg, right[slot], slot, replace, false);
balance(slot, p);
if (size[arg] != 0) throw new Error("double insertion");
+ if(DEBUG) check();
+
// we are replacing an existing node
if (replace) {
if (diff != 0) throw new Error("this should never happen"); // since we already clamped the index
if (p == 0) root = arg;
else if (left[p] == slot) left[p] = arg;
else if (right[p] == slot) right[p] = arg;
+ else throw new Error("should never happen");
left[arg] = left[slot];
right[arg] = right[slot];
size[arg] = size[slot];
parent[arg] = parent[slot];
- if(left[slot] > 0) parent[left[slot]] = arg;
- if(right[slot] > 0) parent[right[slot]] = arg;
+ if(left[slot] != 0) parent[left[slot]] = arg;
+ if(right[slot] != 0) parent[right[slot]] = arg;
objects[slot] = null;
left[slot] = right[slot] = size[slot] = parent[slot] = 0;
-
+ if(DEBUG) check();
+
// we become the child of a former leaf
- } else if (slot <= 0) {
+ } else if (slot == 0) {
int[] left = wentLeft ? BalancedTree.left : BalancedTree.right;
int[] right = wentLeft ? BalancedTree.right : BalancedTree.left;
+ // FEATURE: Might be doing too much work here
left[arg] = slot;
- left[p] = arg;
- right[arg] = -1 * p;
+ right[arg] = 0;
parent[arg] = p;
+ left[p] = arg;
balance(arg, p);
// we take the place of a preexisting node
} else {
+ if(DEBUG) check();
left[arg] = left[slot]; // steal slot's left subtree
- left[slot] = -1 * arg;
+ left[slot] = 0;
right[arg] = slot; // make slot our right subtree
parent[arg] = parent[slot];
parent[slot] = arg;
+ if(left[arg] != 0) parent[left[arg]] = arg;
if (slot == root) {
root = arg;
balance(slot, arg);
} else {
// fast path: it has no children
- if (left[slot] <= 0 && right[slot] <= 0) {
+ if (left[slot] == 0 && right[slot] == 0) {
if (p == 0) root = 0;
else {
int[] side = left[p] == slot ? left : right;
}
// fast path: it has no left child, so we replace it with its right child
- } else if (left[slot] <= 0) {
+ } else if (left[slot] == 0) {
if (p == 0) root = right[slot];
else (left[p] == slot ? left : right)[p] = right[slot]; // fix parent's pointer
parent[right[slot]] = p;
balance(right[slot], p);
// fast path; it has no right child, so we replace it with its left child
- } else if (right[slot] <= 0) {
+ } else if (right[slot] == 0) {
if (p == 0) root = left[slot];
else (left[p] == slot ? left : right)[p] = left[slot]; // fix parent's pointer
parent[left[slot]] = p;
int left_childs_rightmost = delete(sizeof(left[slot]) - 1, left[slot], slot);
left[left_childs_rightmost] = left[slot];
right[left_childs_rightmost] = right[slot];
- if(left[slot] > 0) parent[left[slot]] = left_childs_rightmost;
- if(right[slot] > 0) parent[right[slot]] = left_childs_rightmost;
+ if(left[slot] != 0) parent[left[slot]] = left_childs_rightmost;
+ if(right[slot] != 0) parent[right[slot]] = left_childs_rightmost;
parent[left_childs_rightmost] = parent[slot];
if (p == 0) root = left_childs_rightmost;
else (left[p] == slot ? left : right)[p] = left_childs_rightmost; // fix parent's pointer
}
}
+ protected void finalize() { clear(); }
+
// Debugging ///////////////////////////////////////////////////////////////////////////
+ public void check() { check(false); }
+ public void check(boolean expensive) {
+ if(expensive) System.err.println("--> Running expensive balanced tree checks");
+ try {
+ if(expensive)
+ for(int i=0;i<NUM_SLOTS;i++)
+ if(left[i] < 0 || right[i] < 0) throw new Error("someone inserted a negative number");
+ if(parent[root] != 0) throw new Error("parent of the root isn't 0");
+ if(left[0] != 0 || right[0] != 0 || size[0] != 0 || parent[0] != 0)
+ throw new Error("someone messed with [0]");
+
+ int c = 0;
+ int n = leftmost(root);
+ while(n != 0) { c++; n = next(n); }
+ if(c != size[root]) throw new Error("size[] mismatch");
+
+ if(root != 0) check(root);
+ } catch(Error e) {
+ printTree();
+ throw e;
+ }
+ }
+
+ private void check(int node) {
+ //if(next(node) != next2(node)) throw new Error("next(" + node + ") != next2(" + node + ")");
+ //if(prev(node) != prev2(node)) throw new Error("prev(" + node + ") != prev2(" + node + ")");
+
+ if(left[node] > 0) {
+ if(parent[left[node]] != node) throw new Error("parent node mismatch on left child of " + node);
+ check(left[node]);
+ }
+ if(right[node] > 0) {
+ if(parent[right[node]] != node) throw new Error("parent node mismatch on right child of " + node);
+ check(right[node]);
+ }
+ }
+
public void printTree() {
if(root == 0) System.err.println("Tree is empty");
else printTree(root,0,false);
}
+
private void printTree(int node,int indent,boolean l) {
for(int i=0;i<indent;i++) System.err.print(" ");
- if(node < 0) System.err.println((l?"Prev: " : "Next: ") + -node);
- else if(node == 0) System.err.println(l ? "Start" : "End");
+ if(node == 0) System.err.println("None");
else {
System.err.print("" + node + ": " + objects[node]);
- System.err.println(" Parent: " + parent[node]);
+ System.err.println(" Parent: " + parent[node] + " Size: " + size[node]);
printTree(left[node],indent+1,true);
printTree(right[node],indent+1,false);
}
}
+
+ /*public static void main(String[] args) {
+ BalancedTree t = new BalancedTree();
+ for(int i=0;i<args.length;i++)
+ t.insertNode(i,args[i]);
+ t.printTree();
+ for(int n = t.leftmost(t.root); n != 0; n = t.next(n)) {
+ System.err.println("Next: " + n);
+ }
+ for(int n = t.rightmost(t.root); n != 0; n = t.prev(n)) {
+ System.err.println("Prev: " + n);
+ }
+ }*/
}
projects / org.ibex.core.git / blobdiff